Question regarding applying for an associate position

Hi guys,

When attempting to network via cold call/email to seek out an informational interview, does anyone view this as a waste of time trying to get your foot in the door for even an informational interview (obviously with hopes of getting an actual interview) if a firm hasn't explicitly stated that they are hiring? In other words, does a firm need to necessarily have a job posting available for an associate position for a chance at landing the job? I do know networking regardless is invaluable in terms of future relationships and connections, but in this scenario I am just asking from a perspective of trying to network with someone at a firm that you a specifically going for.

Thanks